Method for the Preparation of Polymeric Conjugates of Doxorubicin with Ph-Controlled Release of the Drug

Abstract

A method for the preparation of polymeric conjugates of N-(2-hydroxypropyl)methacrylamide and a methacryloylaminoacylhydrazone of doxorubicin with pH-controlled release of the drug, comprising the following three steps of synthesis: a. preparation of a monomeric methacryloylaminoacylhydrazine, wherein the aminoacyl is derived from an amino acid or oligopeptide, by reaction of a methacryloyl halide with the respective peptide, amino acid, or a derivative thereof, and subsequent hydrazinolysis, b. synthesis of a polymeric precursor by direct copolymerization of N-(2-hydroxypropyl)methacrylamide with the methacryloylaminoacylhydrazine, and c. binding of doxorubicin to the polymeric precursor by reaction thereof with doxorubicin hydrochloride.

1 . A method for the preparation of polymeric conjugates of N-(2-hydroxypropyl)methacrylamide and a methacryloylaminoacylhydrazone of doxorubicin with pH-controlled release of the drug, characterized by the following three steps of the synthesis:
 a. preparation of a monomeric methacryloylaminoacylhydrazine, wherein the aminoacyl is derived from an amino acid or oligopeptide, by reaction of a methacryloyl halide with the respective peptide, amino acid, or a derivative thereof, and subsequent hydrazinolysis,   b. synthesis of a polymeric precursor by direct copolymerization of N-(2-hydroxypropyl)methacrylamide with the methacryloylaminoacylhydrazine, and   c. binding of doxorubicin to the polymeric precursor by reaction thereof with doxorubicin hydrochloride.   
   
   
       2 . The method according to  claim 1 , characterized in that the acylation in step ( 1   a ) is carried out by reaction of the methyl ester hydrochloride of the respective amino acid or oligopeptide with methacryloyl chloride in a chlorinated hydrocarbon in the presence of anhydrous sodium carbonate. 
   
   
       3 . The method according to  claim 1 , characterized in that the hydrazinolysis is carried out by reaction of the methyl ester of the methacryloylated amino acid or oligopeptide with hydrazine hydrate in the presence of a strong base. 
   
   
       4 . The method according to  claim 1 , characterized in that in step ( 1   b ) radical copolymerization of N-(2-hydroxypropyl)methacrylamide with the methacryloylaminoacylhydrazine is carried out, initiated by thermally decomposable initiators based on azo or peroxy initiators, preferably azobis(isobutyronitrile), azobis(isocyanovaleric acid), or diisopropyl percarbonate. 
   
   
       5 . The method according to  claim 4 , characterized in that the polymerization is carried out in a solvent selected from either lower C 1  to C 5  alcohols, or an aprotic polar solvent. 
   
   
       6 . The method according to  claim 5 , characterized in that the solvent is selected from methanol, ethanol, dimethylformamide, or dimethylsulfoxide. 
   
   
       7 . The method according to  claim 6 , characterized in that when the initiator is selected from azobis(isobutyronitrile) or azobis(isocyanovaleric acid), the polymerization is carried out at 45 to 70° C., and when diisopropyl percarbonate is used as the initiator, the polymerization is carried out at 30 to 60° C. 
   
   
       8 . The method according to  claim 1 , characterized in that the reaction of the polymeric precursor in step ( 1   c ) is carried out in a solvent selected from anhydrous C 1  to C 5  alcohols or polar aprotic solvents, under catalysis by acetic acid, and the resulting conjugate is precipitated with ethyl acetate. 
   
   
       9 . The method according to  claim 8 , characterized in that the solvent is selected from methanol, dried ethanol, dimethylformamide, or dimethylsulfoxide. 
   
   
       10 . The method according to  claim 9 , characterized in that the starting concentration of the polymer is selected within the range of 100 to 190 mg/ml and the concentration of acetic acid within that of 30 to 80 mg/ml. 
   
   
       11 . The method according to  claim 10 , characterized in that the concentration of the polymer is 170 mg/ml and that of acetic acid 55 mg/ml at 25° C. 
   
   
       12 . The method according to  claim 1 , characterized in that the resulting product is purified by gel filtration.